Two-Dimensional Arrays of Holes with Sub-Lithographic Diameters Formed by Block Copolymer Self-Assembly

ABSTRACT

Methods for fabricating sublithographic, nanoscale microstructures in two-dimensional square and rectangular arrays utilizing self-assembling block copolymers, and films and devices formed from these methods are provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. Ser. No. 11/657,273, filed Jan.24, 2007.

TECHNICAL FIELD

Embodiments of the invention relate to methods of fabricatingnanostructures by use of thin films of self-assembling block copolymers,and devices resulting from those methods.

BACKGROUND OF THE INVENTION

As the development of nanoscale mechanical, electrical, chemical andbiological devices and systems increases, new processes and materialsare needed to fabricate nanoscale devices and components. Opticallithographic processing methods are not able to accommodate fabricationof structures and features at the nanometer level. The use of selfassembling diblock copolymers presents another route to patterning atnanometer dimensions. Diblock copolymer films spontaneously assemblyinto periodic structures by microphase separation of the constituentpolymer blocks after annealing, for example by thermal annealing abovethe glass transition temperature of the polymer or by solvent annealing,forming ordered domains at nanometer-scale dimensions. Following selfassembly, one block of the copolymer can be selectively removed and theremaining patterned film used as an etch mask for patterning nanosizedfeatures into the underlying substrate. Since the domain sizes andperiods (L_(o)) involved in this method are determined by the chainlength of a block copolymer (MW), resolution can exceed other techniquessuch as conventional photolithography, while the cost of the techniqueis far less than electron beam (E-beam) lithography or EUVphotolithography, which have comparable resolution.

The film morphology, including the size and shape of themicrophase-separated domains, can be controlled by the molecular weightand volume fraction of the AB blocks of a diblock copolymer to producelamellar, cylindrical, or spherical morphologies, among others. Forexample, for volume fractions at ratios greater than about 80:20 of thetwo blocks (AB) of a diblock polymer, a block copolymer film willmicrophase separate and self-assemble into a periodic spherical domainswith spheres of polymer B surrounded by a matrix of polymer A. Forratios of the two blocks between about 60:40 and 80:20, the diblockcopolymer assembles into a periodic hexagonal close-packed or honeycombarray of cylinders of polymer B within a matrix of polymer A. For ratiosbetween about 50:50 and 60:40, lamellar domains or alternating stripesof the blocks are formed. Domain size typically ranges from 5-50 nm.

Periodic cylindrical structures have been grown in parallel andperpendicular orientations to substrates. A primary requirement forproducing perpendicular cylinders by thermal annealing is that thesubstrate floor must be neutral wetting to the blocks of the copolymer.Periodic hexagonal close-packed cylinders can be useful as etch masks tomake structures in an underlying substrate for applications such asmagnetic storage devices. However, that layout is not useful for makingstructures such as DRAM capacitors, which require a rectangular orsquare shaped array layout.

Graphoepitaxy techniques using substrate topography have been used in anattempt to influence the orientation, ordering and registration of themicrophase-separated domains. Although one-dimensional arrays have beenformed in trenches, no efforts have been made to address ordering of thedomains over a large area, or to control the location and orientation ofordered domains in two dimensions.

Although there is a single report of forming ordered sphere-formingblock copolymer films by Cheng et al. (Nano Lett., 6 (9), 2099-2103(2006)), these have been limited to one-dimensional ordered arrays withadjacent arrays not aligned, the cylinders being off-set along they-axis in neighboring trenches.

It would be useful to provide methods of fabricating films oftwo-dimensional arrays of ordered nanostructures that overcome theseproblems.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described below with reference to thefollowing accompanying drawings, which are for illustrative purposesonly. Throughout the following views, the reference numerals will beused in the drawings, and the same reference numerals will be usedthroughout the several views and in the description to indicate same orlike parts.

FIGS. 1A-4A illustrate diagrammatic top plan views of a portion of asubstrate during various stages of fabrication of a film composed of atwo-dimensional rectangular array of perpendicular oriented cylinders ina polymer matrix according to an embodiment of the present disclosure.FIGS. 1B/1C-4B/4C are elevational, cross-sectional views of thesubstrate fragment depicted in FIGS. 1A-4A, taken along lines1B/1C-1B/1C to lines 4B/4C-4B/4C, respectively.

FIGS. 5A-11C illustrate various stages of the fabrication of a filmcomposed of a two-dimensional square array of perpendicular orientedcylinders in a polymer matrix according to another embodiment of thepresent disclosure. FIGS. 5A-5C illustrate elevational, cross-sectionalviews of a portion of a substrate during stages of producing a materiallayer. FIG. 6 is a cross-sectional view of the substrate depicted inFIG. 5C in a subsequent step with a self-assembling block copolymermaterial within trenches. FIGS. 7A-11A are diagrammatic top plan viewsof a portion of the substrate of FIG. 6, during subsequent stages of thefabrication of a film composed of a two-dimensional square array ofcylinders in a polymer matrix. FIGS. 7B-11B are elevational,cross-sectional views of the substrate depicted in FIGS. 7A-11A, takenalong lines 7B-7B to lines 11B-11B, respectively. FIG. 11C is across-sectional view of the substrate of FIG. 10A in a subsequentprocessing step showing selective removal of the matrix of the annealedfilm in another embodiment.

FIGS. 12A-18A illustrate diagrammatic top plan views of a portion of asubstrate during various stages of fabrication of a film composed of atwo-dimensional rectangular array of perpendicular oriented and paralleloriented cylinders in a polymer matrix according to another embodimentof the present disclosure. FIGS. 12B, 13B and 15B-18B are elevational,cross-sectional views taken along lines B-B of the substrate depicted inFIGS. 12A, 13A and 15A-18A, respectively. FIG. 14 is an elevational,cross-sectional view of the substrate of FIG. 13A in a subsequentprocessing step.

DETAILED DESCRIPTION OF THE INVENTION

The following description with reference to the drawings providesillustrative examples of devices and methods according to embodiments ofthe invention. Such description is for illustrative purposes only andnot for purposes of limiting the same.

In the context of the current application, the term “semiconductorsubstrate” or “semiconductive substrate” or “semiconductive waferfragment” or “wafer fragment” or “wafer” will be understood to mean anyconstruction comprising semiconductor material, including but notlimited to bulk semiconductive materials such as a semiconductor wafer(either alone or in assemblies comprising other materials thereon), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” refers to any supportingstructure including, but not limited to, the semiconductive substrates,wafer fragments or wafers described above.

“L_(o)” is the inherent pitch (bulk period or repeat unit) of structuresthat self assemble upon annealing from a self-assembling (SA) blockcopolymer or a blend of a block copolymer with one or more of itsconstituent homopolymers.

In embodiments of the invention, processing conditions are used thatinduce microphase separation of thin films of self assemblingcylindrical-phase diblock copolymers to produce 2-D rectangular andsquare arrays of nanoscale cylinders by constraining one dimension bygraphoepitaxy and the second dimension either by graphoepitaxy or bychemically differentiating the trench floor.

Steps in a method for fabricating two-dimensional (2-D) rectangulararrays of cylinders oriented perpendicular to a substrate from thinfilms of cylindrical phase self assembling (SA) block copolymersaccording to an embodiment of the invention are illustrated in FIGS.1A-4C. The described embodiment is a graphoepitaxy-only technique, whichutilizes topographical features, the sidewalls and ends of trenches, asconstraints to induce orientation and registration ofperpendicularly-oriented cylindrical copolymer domains in both onedimension (single row parallel to the trench sidewalls) and a seconddimension (cylinders registered between adjacent trenches) to achieve2-D rectangular arrays of nanoscale microstructures in the form ofcylinders within a polymer matrix.

Referring to FIGS. 1A-1B, a substrate 10 with an overlying materiallayer 12 is provided, being a silicon layer 10 and a silicon oxide(SiO_(x)) layer 12 in the illustrated example.

To prepare a 2-D rectangular array of cylinders according to a firstembodiment of a method of the invention, the material layer 12 ispatterned to form an array of adjacently aligned trenches 14 a ₁₋₃, 14 b₁₋₃, 14 c ₁₋₃. Each trench is structured with sidewalls 16, a floor orbottom surface 18, a width (w), and a length (l). Substrate 10 isexposed as the floor 18 of the trench, and portions of the materiallayer 12 form a spacer interval 12 a between the trenches. The width (w)of the trenches is equal to about the inherent pitch value (L_(o)) ofthe polymer, typically ranging from about 10-100 nm. The length (l) ofthe trenches is equal to about nL_(o) (“n*L_(o)”), typically rangingfrom about n*10−n*100 nm (with n being the number of features orstructures (i.e., cylinders)). The first edges (ends or tips) 20 a andthe second edges 20 b of each adjacent trench (e.g., trenches 14 a ₁-14b ₁-14 c ₁) are aligned, as shown in FIG. 1A. As such, each adjacenttrench is substantially the same the length (l). In some embodiments,the trench dimension is about 55-80 nm wide (w) and 1600-2400 nm inlength (l). The depth (D) of the trenches can range from about 50-500nm. The spacing or pitch distance (p_(t)) between adjacent trenches canvary but is at least 2L_(o).

The trenches can be formed using a lithographic tool having an exposuresystem capable of patterning at the scale of L_(o) (10-100 nm). Suchexposure systems include, for example, extreme ultraviolet (EUV)lithography, proximity X-rays, and electron beam lithography, as knownand used in the art. Conventional photolithography can attain ˜58 nmfeatures.

The trench sidewalls 16 and edges 20 a, 20 b influence the structuringof the array of cylinders within the trenches. The boundary conditionsof the trench sidewalls 16 impose order in the x-direction (x-axis) andthe ends 20 impose order in the y-direction (y-axis) to impose astructure wherein each trench contains n number of features (i.e.,cylinders). Factors in forming a single 1-D array of cylinders alignedwithin the center and for the length of each trench include the width ofthe trench, the formulation of the block copolymer to achieve thedesired pitch (L_(o)), and the thickness (t) of the copolymer film. Toachieve a single array (row) of cylinders within each trench, the trenchis constructed to have a width (w) of about the L_(o) value of thepolymer and a length (l) of nL_(o). The application and annealing of ablock copolymer material having an inherent pitch value of L_(o) willresult in a single array of “n” cylinders in the middle of a polymermatrix for the length (l) of the trench, with each cylinder beingseparated by a value of L_(o).

For example, a block copolymer having a 35-nm pitch (L_(o) value)deposited into a 75-nm wide trench will, upon annealing, result in azigzag pattern of 35-nm diameter cylinders that are offset by a halfdistance for the length of the trench, rather than a single line ofcylinders down the center of the trench. As the L_(o) value of thecopolymer is increased, for example, by forming a ternary blend by theaddition of both constituent homopolymers, there is a shift from tworows to one row of cylinders within the center of the trench.

The lithographically-defined alignment of the trench edges 20 a, 20 bimposes a second dimension of ordering such that each one-dimensional(1-D) array of cylinders (i.e., in trench 14 b ₁) will line up with theadjacent 1-D arrays of cylinders (i.e., in trenches 14 a ₁ and 14 c ₁).Stresses due to trench length and/or width mismatch with the inherentpitch of the block copolymer can be relieved by elliptical variance fromcircularity in the x- or y-axis direction, as described, for example, byCheng et al. (Nano Lett., 6 (9), 2099-2103 (2006)).

As shown in FIGS. 1A-1B, an array or string of three adjacent trenches14 a-c has been etched into material layer 12 (e.g., oxide). Thetrenches are structured such that the surfaces of the sidewalls 16 andedges 20 a, 20 b are preferential wetting by the minority block of thecopolymer and the trench floors 18 are neutral wetting (equal affinityfor both blocks of the copolymer) to allow both blocks of the copolymermaterial to wet the floor of the trench. Entropic forces drive thewetting of a neutral-wetting surface by both blocks, resulting in aperpendicular orientation of the self-assembled morphology.

A neutral wetting surface can be provided, for example, by applying aneutral wetting polymer to form a neutral wetting film 22 on the surfaceof the substrate 10 forming the trench floors 18, as illustrated inFIGS. 1A-1B. In the use of a SA diblock copolymer composed of PS-b-PMMA,a random PS:PMMA copolymer brush layer (P(S-r-MMA)), which exhibitsnon-preferential or neutral wetting toward PS and PMMA can be applied byspin-coating onto the trench floor 18 (i.e., the surface of substrate10). The brush can be affixed by grafting (on an oxide substrate) or bycross-linking (any surface) using UV radiation. In an embodiment shownin FIG. 1C, a random copolymer solution can be applied to substrate 10′as a blanket film 22′ before deposition of the material layer 12′. Forexample, a random copolymer solution composed of PS and PMMA (58% PS)can be applied to the surface of the substrate 10 as a layer about 5-10nm thick and end-grafted by heating at about 160° C. for about 48 hours.Etching through the material layer 12′ to form the trenches 14′ thenexposes the underlying random copolymer film layer 22′ as the floor 18′of the trench.

A surface that is neutral wetting to PS-b-PMMA can also be prepared byspin coating a photo- or thermally cross-linkable random copolymer suchas benzocyclobutene- or azidomethylstyrene-functionalized randomcopolymers of styrene and methyl methacrylate (e.g.,poly(styrene-r-benzocyclobutene-r-methyl methacrylate(P(S-r-PMMA-r-BCB)) onto the surface of the substrate 10 within thetrenches and thermally crosslinking the polymer (e.g., 190° C., 4 hours)to form a cross-linked polymer mat. Capillary forces pull the randomcopolymer to the bottom of deep trenches. Non-crosslinked polymermaterial can be subsequently removed. In another embodiment, thecross-linkable polymer can be applied as a blanket film 22′ to thesubstrate 10′ before deposition of the material layer 12′, and exposedupon etching of the trenches 14′, as depicted in FIG. 1C. Anotherneutral wetting surface for PS-b-PMMA can be provided byhydrogen-terminated silicon, which can be prepared by a conventionalprocess, for example, by a fluoride ion etch of silicon (with nativeoxide present, about 12-15 Å) (e.g., as substrate 10), for example, byimmersion in aqueous solutions of hydrogen fluoride (HF) and buffered HFor ammonium fluoride (NH₄F), HF vapor treatment, etc., by exposure tohot H₂ vapor or by a hydrogen plasma treatment (e.g., atomic hydrogen).

The surface of the sidewalls 16 and the edges 20 a, 20 b of the trenchesare preferential wetting by one of the components of the block copolymerto induce formation of the cylinders down the middle of each trench asthe blocks self-assemble. For example, silicon oxide (SiO_(x)) exhibitspreferential wetting toward the PMMA block to result in the assembly ofa thin interface layer of PMMA on the trench sidewalls as well as PMMAcylinders in the center of a PS matrix within each trench. Otherpreferential wetting surfaces to PMMA can be provided, for example, bysilicon nitride, silicon oxycarbide, and PMMA polymer grafted to asidewall material such as silicon oxide, and resist materials such assuch as methacrylate based resists. Upon annealing, the PMMA block ofthe PS-b-PMMA copolymer layer will segregate to the sidewalls and edgesof the trench to form a wetting layer (33 in FIGS. 3A-3C). The materiallayer 12 itself can be a preferential wetting material (e.g., SiO_(x)),although a layer of a preferential wetting material can be applied ontothe surfaces of the trenches. For example, a polymethylmethacrylate(PMMA) that is modified with a moiety containing one or more hydroxyl(—OH) groups (e.g., hydroxyethylmethacrylate) can be applied by spincoating and then heating (e.g., to about 170° C.) to allow the terminalOH groups to end-graft to the oxide sidewalls 16 and edges 20 a, 20 b ofthe trenches. Non-grafted material can be removed from the neutralwetting layer 22 by rinsing with an appropriate solvent (e.g., toluene).See, for example, Mansky et al., Science 275: 1458-1460 (1997)).

Referring now to FIGS. 2A-2B, a cylindrical-phase SA block copolymermaterial 24 having an inherent pitch at or about L_(o) (or a ternaryblend of block copolymer and homopolymers blended to have a pitch at orabout L_(o)) is then deposited, typically by spin casting(spin-coating), onto the floor 18 of the trenches. The block copolymermaterial can be deposited onto the patterned surface by spin castingfrom a dilute solution (e.g., about 0.25-2 wt % solution) of thecopolymer in an organic solvent such as dichloroethane (CH₂Cl₂) ortoluene, for example.

The copolymer material layer 24 is deposited into the trenches to athickness (t) of less than or about equal to the L_(o) value of thecopolymer material to up to about 3L_(o), such that the copolymer filmlayer will self assemble upon annealing to form a single row ofperpendicular cylindrical domains having a diameter of about L_(o)(e.g., 25-35 nm) in the middle of a polymer matrix within each trench.The film thickness can be measured, for example, by ellipsometry.

Depending on the depth (D) of the trenches, the cast block copolymermaterial 24 can fill the trenches as in FIG. 2B where the trench depthis about equal to L_(o) (D˜L₀), or form a thin film 24′ over the trenchfloor 18′ or optionally over the trench sidewalls 16′ and edges 20 a′,20 b′ as in FIG. 2C where the trench depth is greater than L_(o) (D>L₀),e.g., a meniscus. The height (h) of the assembled cylinders (FIGS.3B-3C) corresponds approximately to the thickness (t) of the depositedcopolymer material 24, 24′ within the trench. Although not shown, a thinfilm of the copolymer material 24 can be deposited onto the surface ofthe oxide layer 12; this material will not self-assemble, as it is notthick enough to form structures.

Although diblock copolymers are used in the illustrative embodiment,other types of block copolymers (i.e., triblock or triblock ormultiblock copolymers) can be used. Examples of diblock copolymersinclude poly(styrene-block-methyl methacrylate) (PS-b-PMMA),polyethyleneoxide-polyisoprene, polyethyleneoxide-polybutadiene,polyethyleleoxide-polystyrene, polyetheleneoxide-polymethylmethacrylate,polystyrene-polyvinylpyridine, polystyrene-polyisoprene (PS-b-PI),polystyrene-polybutadiene, polybutadiene-polyvinylpyridine, andpolyisoprene-polymethylmethacrylate, among others. Examples of triblockcopolymers include poly(styrene-block methyl methacrylate-block-ethyleneoxide). An examples of a PS-b-PMMA copolymer material (L_(o)=35 nm) iscomposed of about 70% PS and 30% PMMA with a total molecular weight(M_(n)) of 67 kg/mol, to form ˜20 nm diameter cylindrical PMMA domainsin a matrix of PS.

The block copolymer material can also be formulated as a binary orternary blend comprising a SA block copolymer and one or morehomopolymers of the same type of polymers as the polymer blocks in theblock copolymer, to produce blends that swell the size of the polymerdomains and increase the L_(o) value of the polymer. The volume fractionof the homopolymers can range from 0 to about 40%. An example of aternary diblock copolymer blend is a PS-b-PMMA/PS/PMMA blend, forexample, 46K/21K PS-b-PMMA containing 40% 20K polystyrene and 20Kpoly(methylmethacrylate). The L_(o) value of the polymer can also bemodified by adjusting the molecular weight of the block copolymer.

Optionally, ellipticity (“bulging”) can be induced in the structures bycreating a slight mismatch between the trench and the spacer widths andthe inherent pitch (L_(o)) of the block copolymer or ternary blend, asdescribed, for example, by Cheng et al., “Self-assembled One-DimensionalNanostructure Arrays,”, Nano Lett., 6 (9), 2099-2103 (2006), which thenreduces the stresses that result from such mismatches.

Referring now to FIGS. 3A-3B, the block copolymer film 24 is thenannealed as by thermal annealing above the glass transition temperatureof the component blocks of the copolymer material to cause the polymerblocks to separate and self assemble according to the pattern ofwettability on the underlying surfaces of the trenches to form theself-assembled block copolymer structure 28. For example, a PS-b-PMMAcopolymer film can be annealed at a temperature of about 180-195° C. ina vacuum oven for about 1-24 hours to achieve the self-assembledmorphology. The film can also be solvent annealed, for example, byslowly swelling both blocks of the film with a solvent, then slowlyevaporating the solvent.

The annealed copolymer film comprises a rectangular array ofperpendicularly oriented cylindrical domains 30 of a first block of thecopolymer within a matrix 32 of a second block, the cylindrical domainsin one dimension at a pitch distance of about L_(o) and aligned withcylindrical domains in a second dimension at a pitch distance of about2*L_(o). The annealed copolymer film can be contained within adjacentlyspaced apart trenches with the ends (edges) 20 a, 20 b of the trenchesbeing aligned, and with the cylindrical domains within each trench in asingle array and at a pitch distance of about L_(o) and aligned with thecylindrical domains in adjacent trenches at a pitch distance of about2*L_(o).

The constraints provided by the width (w) of trenches and the characterof the copolymer composition combined with a neutral wetting trenchfloor 18 and preferential wetting sidewalls 18 and edges 20 a, 20 b,results, upon annealing, in a one-dimensional (1-D) array (single row)of perpendicularly-oriented, cylindrical domains 30 of PMMA within amatrix 32 of PS within each trench 14 a-c, with n structures accordingto the length of the trench, and a thin layer 33 of PMMA wetting thesidewalls 18.

The additional feature of the alignment of the trench edges 20 a, 20 bin combination with a pitch distance (p_(t)) of adjacent trenchessubstantially equal to 2L_(o), achieves two-dimensional (2-D)rectangular arrays 28 a-28 c of cylindrical domains 30 in which thepattern period or pitch distance (p_(c)) of the cylinders 30 within asingle trench (e.g., 14 a ₃) is substantially equal to L_(o) and thepitch distance (p_(c2)) between the cylinders 30 of adjacent trenches(e.g., 14 a ₃ and 14 b ₃) is substantially equal to 2*L_(o) (2L_(o)) asdepicted in FIG. 3A.

The resulting morphologies of the block copolymer (i.e., perpendicularorientation of cylinders) can be examined, for example, using atomicforce microscopy (AFM), transmission electron microscopy (TEM), andscanning electron microscopy (SEM).

After annealing and the copolymer material is ordered, one of the blockcomponents can be selectively removed from the film, leaving either thecylindrical domains 30 (FIG. 4B) or the matrix 32 (FIG. 4C) resulting inrectangular arrays 28 a-28 c of openings or coverings (structures).After selective removal of one of the polymer domains, the resultingthin films can be used, for example, as a lithographic template or maskto pattern the underlying substrate 10 in a semiconductor processing todefine regular patterns in the nanometer size range (i.e., about 10-100nm).

For example, referring to FIGS. 4A-4B, selective removal of the PMMAphase cylinders 30 will result in 2-D rectangular arrays of openings 34within a thin film of polystyrene (PS) 32 within the trenches 14 a-cwith the oxide layer 12 a remaining a spacer between each trench.Removal of the PMMA phase cylinders 30 can be performed, for example, byapplication of an oxygen (O₂) plasma, or by a chemical dissolutionprocess such as acetic acid sonication by first irradiating the sample(ultraviolet (UV) radiation, 1 J/cm̂2 254 nm light), then ultrasonicatingthe film in glacial acetic acid, ultrasonicating in deionized water, andrinsing the film in deionized water to remove the degraded PMMA.

In another embodiment illustrated in FIG. 4C, the selective removal of aPMMA phase matrix 32 will provide 2-D rectangular arrays of PS phasecylinders 30 and openings 34′. Such an embodiment would require amajority PMMA block copolymer and sidewalls composed of a material thatis selectively PMMA-wetting (e.g. oxide).

The resulting porous PS film can be used as an etch mask to pattern(arrows ↓↓) the underlying substrate 10, for example, by a non-selectiveRIE etching process, to form a rectangular array of openings 35 insubstrate 10 (shown in phantom in FIGS. 4A-4B) for the fabrication ofdevices such as capacitors. Further processing can then be performed asdesired.

A method according to another embodiment of the invention utilizing agraphoepitaxy-only technique is illustrated with reference to FIGS.5A-11C, for forming two-dimensional (2-D) square arrays ofperpendicularly-oriented cylinders in a polymer matrix.

In an embodiment to form a 2-D square array, a construction as describedwith reference to FIGS. 1A-1C can be provided, which includes asubstrate 10′ bearing a neutral wetting surface, for example, byapplication of a neutral wetting material layer 22″, and an overlyingmaterial layer 12″ having trenches 14 a ₁₋₃″-14 c ₁₋₃″ formed therein toexpose the neutral wetting material layer 22″ as the trench floors 18″.In one embodiment, for example, a neutral wetting material layer 22″such as an end-grafted neutral wetting random (PS:PMMA) copolymer brushcan be formed on the substrate 10″, and then layer 12″ deposited, asdescribed with reference to FIG. 1C. Neutral wetting trench floors 18″can also be provided as H-terminated silicon, which can be prepared, forexample, by a fluoride ion etch of a silicon substrate 10″ (with nativeoxide present, about 12-15 Å), for example, by immersion in aqueoussolutions of hydrogen fluoride (HF) and buffered HF or ammonium fluoride(NH₄F), HF vapor treatment, etc., or by exposure to hot H₂ vapor or by ahydrogen plasma treatment (e.g., atomic hydrogen). As in FIGS. 1A-1C,each trench is separated by a spacer interval 12 a″ of the materiallayer 12″ of a width (w_(i)) of about L_(o).

In this embodiment, the sidewalls 16″ of the material layer 12″ arepreferential wetting to the major block of the SA block copolymer, beingPS in the illustrated example. Preferential wetting surfaces to PS canbe provided, for example, by a metal such as gold or a PS-basedphotoresist containing a photoacid generator. For example, the materiallayer 12″ itself can be composed of metal (e.g., gold), or the sidewalls16″ of the material layer 12″ can be coated with a thin film of metal,for example, by evaporation, sputtering, or a spin-on technique, withremoval of the metal from the trench floors 18″ (e.g., by etching). Forexample, a metal (e.g., gold) layer of about 2-10 nm can be applied bythermal evaporation onto surfaces of the trenches formed within amaterial layer 12″ of oxide, which surface can be precoated with a seedlayer (e.g., chromium) as an adhesive interface.

In an embodiment with reference to FIG. 5A, a neutral wetting layer 22″(e.g., a random copolymer, H-terminated silicon, etc.) is formed on thesubstrate 10″. Then, as illustrated, a photoresist layer 36″ is appliedonto the neutral wetting layer 22″, baked, patterned and developed toform a series of grooves 37″. For example, a random copolymer brush ofPS (58% vol.) and PMMA can be grafted onto a silicon substrate toprovide a neutral wetting layer 22″, and a PMMA resist 36″ applied(e.g., by spin-coating), baked (about 130° C.) to remove residualsolvent, patterned (e.g., by electron beam lithography), and developedby immersing in solvent. As shown in FIG. 5B, a layer of metal can thenbe deposited to form the material layer 12″. The remaining photoresist36″ and overlying metal can then be removed. Such a liftoff processresults in a structure as in FIG. 5C (and in top plan view in FIG. 1A).For example, a layer of chromium and of gold can be sequentiallydeposited by evaporation, and the PMMA photoresist and overlyingdeposited metal removed to result in gold features with grooves betweenthe features. As shown, a series of metal features (e.g., gold) form thematerial layer 12″ with sidewalls 16″ and spacer intervals 12 a″ betweenadjacent trenches (e.g., between 14 a ₃″, 14 b ₃″, and 14 c ₃″), andgrooves or trenches 14 a ₁₋₃″-14 c ₁₋₃″ with the exposed neutral wettinglayer 22″ as the trench floors 18″. Upon annealing a block copolymerfilm (e.g., of PS-b-PMMA) within the trenches, the major block (e.g.,PS) will wet the surface of the sidewalls of the trenches (as shown inFIGS. 7A-7B).

Referring now to FIG. 6, a cylindrical-phase SA block copolymer material24″ (as described with reference to FIGS. 2A-2B) is then deposited intothe trenches and annealed. The resulting self-assembled block copolymerstructure 28″, illustrated in FIGS. 7A-7B, is composed of 2-Drectangular arrays 28 a″-28 c″ of cylinders 30″ of the minor block(e.g., PMMA) within a matrix 32″ of the major block (e.g., PS), whichalso wets the sidewalls 16″ of the trenches.

Following the annealing and ordering of the copolymer material 24″, thepolymer film 28″ is crosslinked to fix and enhance the strength of theself-assembled polymer blocks. The polymers may be structured toinherently crosslink (e.g., upon UV exposure), or one or both of thepolymer blocks of the copolymer material can be formulated to contain acrosslinking agent, which can be the same crosslinking agent if used informing the neutral wetting film 22″ on the trench floors 18″ (as in thestep of FIGS. 1A-1C).

Referring now to FIGS. 8A-8B, following the crosslinking of the film28″, the spacer interval 12 a″ of the material layer 12″ (e.g., gold)situated between adjacent trenches (e.g., between 14 a ₃″, 14 b ₃″, and14 c ₃″) is then removed, for example, by a selective wet etch with aquaregia, to produce an intermediate structure with new trenches 15 a₁₋₃″-15 b ₁₋₃″ of width (w_(l)) at or about L_(o). As illustrated, theremoval exposes the matrix 32 composed of the major block (e.g., PS) toform the sidewalls 40″ of the trenches 15″, and exposes the neutralwetting layer 22″ as the trench floors 42″.

In an embodiment in which the material layer 12″ is composed of amaterial such as silicon oxide (SiO_(x)), the spacer intervals 12 a″ canbe removed, for example by a fluoride ion wet etch. In an embodiment inwhich the material layer 12″ is composed of a negative resist such as amethacrylate-based photoresist, the spacer intervals 12 a″ betweentrenches 14 a-c″ can be selectively developed and then removed by wetprocessing by applying an appropriate solvent to form new trenches 15a″-15 b″.

As shown, the spacer material 12 a″ has been removed to define thetrench ends or edges 38 a″, 38 b″, and to expose the matrix 32″ (e.g.,of PS) of the first self-assembled block copolymer film 28″ to definethe sidewalls 40″ of trenches 15 a″-15 b″, which are preferentialwetting. The removal of the spacer material 12 a″ is conducted so as notto damage or disrupt the integrity of the first self-assembled blockcopolymer structure 28″. A residual amount of the spacer material 12 a″(e.g. of gold) may remain (not shown) on the surface of the matrix 32″(i.e., sidewalls 40″). The trench edges 38 a″, 38 b″ are aligned withthe edges 20 a″, 20 b″ of trenches 14 a″-14 c″. As such, the length (l)of the trenches 14″, 15″ is nL_(o).

Next, as illustrated in FIGS. 9A-9B, a second SA block copolymermaterial is deposited (e.g., by spin casting) as a film 46″ into thenewly formed trenches 15 a ₁₋₂″45 b ₁₋₂″. The second block copolymermaterial 46″ has a period of L_(o) and is neutral wetting to the trenchfloors 42″, and the major block (e.g., PS) of the second copolymermaterial is preferential wetting to the sidewalls 40″ and trench edges38″, 38 b″. The second copolymer material 46″ can be the same or adifferent composition than the first copolymer material 24″. Thethickness (t) of the cast film 46″ is less than or about equal to theL_(o) value of the second block copolymer material.

The first self-assembled major block (matrix 32″, optionally with aresidual amount of spacer 12 a″ (e.g., gold) thereon) which forms thesidewalls 40″ of trenches 15 a″-15 b″, provides a template or boundarycondition in the x-axis (

) for the registration of the self-assembling second copolymer film 46″.In addition, the edges 38 a, 38 b provide boundary conditions in they-axis (

). The trench floors 42″ are neutral wetting, and the matrix 32″ of thefirst assembled film is preferential wetting to the major block of thesecond copolymer, allowing graphoepitaxy and the formation ofperpendicularly-oriented cylindrical domains within the trenches 15a″-15 b″. Optionally, ellipticity can be induced in the structures bycreating a slight mismatch between the trench width and the inherentpitch (L_(o)) of the block copolymer or ternary blend, as previouslydescribed.

The second copolymer film 46″ is then annealed to form theself-assembled block copolymer structure 48″ depicted in FIGS. 10A-10B.The earlier performed cross-linking step contributes to the structuralintegrity of the first self-assembled film 28″ during the casting andannealing of the second block copolymer film. The annealed copolymerfilm comprises a square array of perpendicularly oriented cylindricaldomains of a first block of the copolymer within a matrix of a secondblock, the cylindrical domains in one dimension in a single row at apitch distance of about L_(o) and aligned with cylindrical domains in asecond dimension at a pitch distance of about L_(o).

Upon annealing, the second block copolymer film self-assembles into 1-Darrays of perpendicularly-oriented (PMMA) cylindrical domains 50″ (e.g.,of PMMA) within a polymer matrix 52″ (e.g., of PS), which are registeredto the sidewalls 40″ (matrix 32″) of the trenches 15 a ₁₋₂″-15 b ₁₋₂″,with the major polymer block (matrix 52″, e.g., of PS) wetting thesidewalls 40″. Each cylinder 50″ is spaced apart within each trench 15a″-15 b″) by a pitch distance (p_(c)″) of L_(o). The cylinders 50″ arealso registered to and aligned with the cylinders 30″ within trenches 14a-c″.

The alignment of the trench edges 38 a″, 38 b″ with edges 20 a″, 20 b″of the first set of trenches 14 a″-14 c″ in combination with a trenchwidth (w) and trench pitch (p_(t)) between adjacent trenches (e.g., 14 a₃″, 15 a ₃″, 14 b ₃″, etc.) of about L_(o) produces a self-assembledfilm 48″ containing two-dimensional (2-D) square arrays 48 a″-48 c″ ofcylinders 30″, 50″, with each cylinder within an array being separatedby a pitch distance (p_(c)) of L_(o).

Referring now to FIGS. 11A-11C, selective removal of one of the polymerdomains (i.e., matrix or cylinders) can then be performed to produce atemplate for use in patterning the substrate 10″. For example, selectiveremoval of the cylindrical domains 30″, 50″ (e.g., of PMMA) will produce2-D square arrays of openings 54″ contained within a polymer matrix 32″,52″ (e.g., of PS), as in FIGS. 11A-11B. Selective removal of the matrixphase 32″, 52″ of the film will provide 2-D square arrays of cylinders30″, 50″ and openings 54″, as shown in FIG. 11C. The resulting film canbe then used in patterning (arrows ↓↓) substrate 10″ to form openings35″ in substrate 10″ (shown in phantom). Processing can then becontinued as desired.

Another method according to an embodiment of the invention, illustratedwith reference to FIGS. 12-18, utilizes both graphoepitaxy (topographicfeatures) and chemical pattern transfer techniques to form a filmcomposed of 2-D rectangular arrays of parallel- andperpendicular-oriented cylinders in a polymer matrix. Graphoepitaxy isused to form arrays in one dimension, and a chemical pattern transfertechnique is used to control formation of the arrays in a seconddimension.

In the present embodiment, chemical pattern transfer is applied todifferentiate and create patterns of wetting preferences in discreteareas on the floors of adjacently positioned trenches as a series ofstripes oriented perpendicular to the trench sidewalls. The differingwetting patterns impose ordering on block copolymer films that are thencast on top of the substrate and annealed.

As shown in FIGS. 12A-12B, in a first step of preparing a patterned orchemically activated surface on the trench floor (18′″), a neutralwetting random copolymer brush 22′″ (e.g., a random PS-r-PMMA polymer)is coated onto a substrate 10′″, which can be an inherently preferentialwetting material such as silicon (with native oxide), oxide (e.g.,silicon oxide, SiO_(x)), or inorganic film. The brush layer 22′″ iscoated with a layer of photoresist 56′″, which is patterned as shown, byoptical lithography or other suitable method. The polymer brush layer22′″ is then etched using the patterned resist layer 56′″ as a mask toexpose the underlying preferential wetting substrate 10′″, and theresist layer 56′″ is removed.

In another embodiment, layer 22′″ is composed of a photo-crosslinkableneutral wetting polymer as described, for example, in U.S. Pat. No.6,890,703 and U.S. Pat. No. 6,992,115 (Hawker et al.), which can bephotoexposed and selectively crosslinked in the desired regions 60′″ byexposure to light through a reticle. In another embodiment, selectivecrosslinking of the neutral wetting layer 22′″ in defined sections 60′″can be performed with the use of a patterned photoresist mask. Thenon-crosslinked regions can then be removed by wet processing using anappropriate solvent.

The resulting structure, depicted in FIGS. 13A-13B, is patterned withdiscrete sections 58′″ of the exposed preferential wetting substrate10′″ (e.g., silicon with native oxide) adjacent to discrete sections60′″ of the neutral wetting polymer layer 22′″. In some embodiments, thefloor pattern is a series of stripes, the neutral wetting stripes orsections 60′″ with a width (w_(r)) at or about nL_(o) and thepreferential wetting stripes or sections 58′″ with a width (w_(r)) at orabout Lo. In another embodiment, each of the sections 58′″, 60′″ has awidth (w_(r)) at or about L_(o).

A material layer 12′″ (e.g., of SiO_(x)) is then deposited over thesubstrate as illustrated in FIG. 14, and patterned with a series oftrenches to expose the patterned substrate 10′″ as the floor of thetrenches, as shown in FIGS. 15A-15B. In another embodiment, the materiallayer 12′″ can be deposited on the substrate 10′″, the trenches etchedinto the material layer to expose the substrate, and the neutral polymerlayer 22′″ deposited onto the floors of the trenches, masked and thenetched to expose sections 58′″ of the substrate 10′″ within thetrenches.

As illustrated in FIG. 15A, the structure has been patterned with threesets of adjacent trenches 14 a ₁₋₃′″-14 c ₁₋₃′″ of width (w) at or aboutL_(o) and a length (l) of about nL_(o). The widths (w_(s)) of the spacerinterval 12 a′″ of the material layer 12′″ between adjacent trenches(e.g., between 14 a ₃′″, 14 b ₃′″, 14 c ₃′″, etc.) is constant and atleast L_(o), being L_(o) in the present example. Thus, the pitchdistance (p_(t)) of adjacent trenches is about 2*L_(o).

The trench sidewalls 16′″ and edges 20 a′″, 20 b′″ (e.g., of SiO_(x))are preferential wetting to one block (e.g., PMMA) of the copolymer. Thetrench floors 18′″ are defined by the alternating preferential wettingsections 58′″ (substrate 10′″) and neutral wetting sections 60′″ (e.g.,random copolymer brush 22″).

Referring now to FIGS. 16A-16B, with the trench floors chemicallypatterned, a block copolymer 24′″ with cylindrical morphology of pitchL_(o) or a ternary blend of a block copolymer and homopolymersformulated to have pitch L_(o) can then be cast into the trenches to afilm thickness (t) of about L_(o) and annealed. As depicted in FIGS.17A-17B, the block copolymer film will then self assemble in each trenchinto a 1-D array of a perpendicular-oriented cylindrical domain 62″° (ora string of such perpendicular domains) extending the width (w_(r)) ofeach neutral wetting polymer section 60′″ situated between aparallel-oriented cylindrical domain 64′″ (half-cylinder) (or string ofsuch parallel domains) extending the width (w_(r)) of each preferentialwetting section 58′″.

The annealed copolymer film comprises a rectangular array of cylindricaldomains of a first block of the copolymer within a matrix of a secondblock, the cylindrical domains in one dimension comprising a series of nperpendicular oriented cylinders 62′″ between two parallel-orientedcylinders 64′″ in a single row at a pitch distance of about L_(o), withthe cylindrical domains aligned with cylindrical domains in a seconddimension at a pitch distance of about 2*L_(o). The annealed copolymerfilm can be contained within adjacently spaced apart trenches of lengthm*(n+1)*L_(o) with the ends (edges) 20 a′″, 20 b′″ of the trenches beingaligned, and with the cylindrical domains within each trench in a singlearray and at a pitch distance of about L_(o) and aligned with thecylindrical domains in adjacent trenches at a pitch distance of about2*L_(o), such that the single array within each trench comprises aperpendicular oriented cylinder 62′″ or n cylinders between twoparallel-oriented cylinders 64′″.

The edge 66′″ between the sections 58′″, 60′″ provides a boundarycondition for the sharp transition between parallel- andperpendicular-oriented cylinders and imposes order in one-dimension(1-D) within each trench. The resulting structure is an ordered 1-Darray of alternating perpendicular- and parallel-oriented cylinders forthe length (nL_(o)) of each trench. Alternatively, the structure is arepeating series of n perpendicular cylinders separated by a region ofparallel cylinder morphology, e.g., the trench length is m*(n+1)*L_(o),where m is the number of preferential-wetting chemically patternedstripes and n is the number of features or structures (e.g., where m andn are independently 1-50).

The inversion from perpendicular to parallel cylinders that occurs atthe boundary edges 66′″ imposes a second dimensional constraint wherebythe structures in adjacent trenches (rows) are also aligned in a seconddimension. The resulting structure is a 2-D rectangular array ofsublithographic cylindrical structures in alternating perpendicular andparallel orientations.

Referring now to FIGS. 18A-18B, selective removal of one of the polymerdomains (i.e., matrix or cylinders) can then be performed to produce atemplate for use in patterning the substrate 10′″. For example,selective removal of the cylindrical domains 62′″, 64′″(e.g., of PMMA)will produce 2-D rectangular arrays of openings 68′, 70′″ containedwithin a polymer matrix 72′″ (e.g., of PS). The resulting film can bethen used in patterning substrate 10′″. The configuration of theopenings will vary according to the orientation of the cylindricaldomains within the trenches. Only openings 68′″ will extend to thetrench floor 18′″, thus the structure forms an etch mask which canselectively transfer the structural pattern of the perpendicularcylinders 62′″ to the underlying substrate (shown as phantom openings74′″).

Embodiments of the invention provide ordering of domains over a largearea, and control the location and orientation of ordered cylindricaldomains in two dimensions. Such features can be prepared moreinexpensively than by electron beam lithography or EUV photolithography.The feature sizes produced and accessible by this invention cannot beprepared by conventional photolithography.

Example I

Trenches 250 nm deep with widths ranging from 75 nm to 600 nm havingsilicon oxide sidewalls and silicon oxycarbide floors were provided. Onseveral of the wafers, oxide was deposited onto the sidewalls and thetrench floors. Both types of trench floors were treated to be neutralwetting to PS and PMMA.

To get perpendicular cylinders, a random PS:PMMA copolymer solution(about 58% PS) containing a crosslinking agent was cast as a film ofabout 5-10 nm thick onto the features, and annealed at about 160° C. for4 hours. Capillary forces pulled the PS-r-PMMA to the trench floor priorto complete cross-linking, leaving oxide sidewalls that werepreferential-wetting to PMMA. The resulting trench structure hadsidewalls that were preferential wetting with the random copolymer layeras a mat on the bottom of the trenches, which provided a neutral wettingsurface.

A 0.425% solution of cylinder-forming PS-b-PMMA in toluene was then castonto the treated substrates so as to form a film about 30-40 nm thick.The PS-b-PMMA material (46K/21K PS:PMMA; 67K MW) was formulated to formPMMA-phase cylinders (diameter ˜20 nm) at repeat periods (pitch) ofabout 35 nm in the middle of a PS matrix. However, the arrays inadjoining trenches were not aligned.

In about 75 nm wide trenches, two rows of cylinders were formed thatwere slightly offset from each other, forming a “zigzag” structure in aregular registered pattern with each side being equidistant from thesidewall of the trench.

Example 2

Ternary blends (10-40%) of homopolymers (20 K PS, 20 K PMMA) wereprepared in 0.425% solutions of 46K/21K PS-b-PMMA in toluene. Thesesolutions were cast onto the substrates described above at thicknessesof 30-40 nm. The addition of homopolymers swells the domain sizes of thetwo fractions, resulting in an increased inherent pitch value (L_(o)) ofthe polymer.

At 10-20% homopolymers, a two row zigzag pattern of cylinders was formedas seen by SEM. With 30% homopolymers content, the zigzag pattern beganto break down and numerous errors and unusual morphologies wereobserved. When a ternary blend of 46/21 PS-b-PMMA block copolymer with40% 20 PS and 20K PMMA homopolymers was cast and annealed onto the samesubstrate (i.e., 80 nm wide trenches, (P(S-r-BCB-r-MMA)) floor, oxidesidewalls), single rows of perpendicular cylinders with apparentdiameter of about 35 nm formed in the 80 nm wide trenches. At 40%homopolymers, the mixture caused a pitch of about 50 nm, resulting inthe formation of a one-dimensional (1-D) array (single row) ofcylinders. This is an example of graphoepitaxy technique in whichlithographically defined physical features are used to cause ordering ofblock copolymer films. The cylinder arrays in adjacent trenches were notaligned and were off-set along the y-axis.

The results show that the boundary condition of the preferential wettingsidewalls and neutral wetting floor within a trench of width equal tothe inherent pitch value (L_(o)) of the self-assembling polymer filmenforced the formation of a single row of cylinders. The results alsodemonstrate that, by increasing L_(o) so that it is a closer match tothe sidewalls, there is a shift from a two row structure to a one rowstructure.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement which is calculated to achieve the same purpose maybe substituted for the specific embodiments shown. This application isintended to cover any adaptations or variations that operate accordingto the principles of the invention as described. Therefore, it isintended that this invention be limited only by the claims and theequivalents thereof. The disclosures of patents, references andpublications cited in the application are incorporated by referenceherein.

1. A method of fabricating a polymeric material, the method comprising:masking a neutral wetting material situated on a preferential wettingsubstrate to form masked and unmasked sections, each unmasked sectionhaving a width at or about L_(o), and each masked section having a widthat or about nL_(o); removing the unmasked sections of the neutralwetting material to expose the substrate; removing the mask to exposethe sections of the neutral wetting material; depositing an overlyingmaterial over the sections of the substrate and the neutral wettingmaterial; forming a plurality of trenches in the overlying material toexpose the sections of the substrate and the neutral wetting materialsuch that said sections are oriented perpendicular to sidewalls of thetrenches, each trench having preferential wetting sidewalls and ends, awidth of about L_(o), a length of about m*(n+1)*L_(o) where m is thenumber of sections of the preferentially wetting substrate and n is thenumber of perpendicularly oriented cylinders, and m and n areindependently 1-50, the ends of the trenches being aligned, and a pitchdistance between adjacent trenches of at least about 2*L_(o); depositinga block copolymer material within the trenches; and causing the blockcopolymer material to self-assemble into cylinders of a first polymerblock of the block copolymer in a matrix of a second polymer blockwithin each trench, the cylinders situated on the sections of theneutral wetting material in a perpendicular orientation to thesubstrate, and the cylinders situated on the sections of thepreferential wetting layer in a parallel orientation to the substrate,each trench containing m rows of n cylinders with the cylinders withineach trench at a pitch distance of about L_(o) and the cylinders betweenadjacent trenches at a pitch distance of about 2*L_(o).
 2. The method ofclaim 1, wherein the block copolymer material comprises an about 60:40to about 80:20 ratio of a first polymer block to a second polymer block.3. The method of claim 1, wherein the block copolymer comprises a blendof the block copolymer with a homopolymer of the first polymer block,the second polymer block, or both.
 4. The method of claim 1, wherein theblock copolymer material within the trenches has a thickness of aboutL_(o).
 5. The method of claim 1, further comprising forming the neutralwetting material on the substrate.
 6. The method of claim 1, wherein theneutral wetting material comprises a random copolymer.
 7. The method ofclaim 1, wherein the neutral wetting material compriseshydrogen-terminated silicon.
 8. The method of claim 1, wherein thesubstrate comprises silicon.
 9. The method of claim 1, furthercomprising applying a preferential wetting material to the ends andsidewalls of the trenches.
 10. The method of claim 1, wherein thesidewalls and edges comprise a preferential wetting material selectedfrom the group consisting of silicon oxide, silicon nitride, siliconoxycarbide, metal, and resist material.
 11. The method of claim 1,wherein the block copolymer material on the sections of the neutralwetting material self-assembles into a single row of perpendicularoriented cylinders.
 12. The method of claim 1, wherein causing the blockcopolymer material to self-assemble comprises thermally annealing theblock copolymer material.
 13. The method of claim 1, wherein causing theblock copolymer material to self-assemble comprises solvent annealingthe block copolymer material.
 14. The method of claim 1, furthercomprising, after causing the block copolymer material to self-assemble,selectively removing the first polymer blocks to provide openings withinthe matrix of the second polymer block.
 15. The method of claim 14,further comprising, prior to removing the polymer blocks, crosslinkingthe self-assembled block copolymer.
 16. The method of claim 14, furthercomprising etching the substrate through the openings.
 17. A method offabricating a polymeric material, the method comprising: forming aplurality of trenches in a material overlying a substrate, each trenchhaving a preferentially wetting floor, sidewalls and ends, a width ofabout L_(o) and a length, the ends of the trenches being aligned, and apitch distance between adjacent trenches being at least about 2*L_(o);depositing a neutral wetting material onto the floor of the trench;masking the neutral wetting material to form masked and unmaskedsections oriented perpendicular to sidewalls of the trenches, eachunmasked section having a width at or about L_(o), and each maskedsection having a width at or about nL_(o); removing the unmaskedsections of the neutral wetting material to expose sections of thepreferentially wetting floor of the trench; removing the mask to exposesections of the neutral wetting material; depositing a block copolymermaterial within the trenches; and causing the block copolymer materialto self-assemble into cylinders in a polymer matrix within each trench,the cylinders situated on the sections of the neutral wetting materialin a perpendicular orientation to the substrate, and the cylinderssituated on the sections of the preferential wetting layer in a parallelorientation to the substrate, each trench containing m rows of ncylinders with the cylinders within each trench at a pitch distance ofabout L_(o) and the cylinders between adjacent trenches at a pitchdistance of about 2*L_(o).
 18. The method of claim 17, wherein thelength of the trenches is about m*(n+1)*L_(o) where m is the number ofsections of the preferentially wetting substrate and n is the number ofperpendicularly oriented cylinders, and m and n are independently 1-50,19. A polymeric material situated within adjacently spaced aparttrenches, ends of the trenches being aligned; the polymeric materialcomprising a rectangular array of perpendicularly oriented cylindricaldomains of a first block of a block copolymer within a matrix of asecond block of the block copolymer, the cylindrical domains within eachtrench in a single array at a pitch distance of about L_(o) and alignedwith the cylindrical domains in adjacent trenches at a pitch distance ofabout 2*L_(o).
 20. A polymeric material comprising a rectangular arrayof perpendicularly oriented cylindrical domains of a first block of ablock copolymer within a matrix of a second block of the blockcopolymer, the cylindrical domains in one dimension at a pitch distanceof about L_(o) and aligned with cylindrical domains in a seconddimension at a pitch distance of about 2*L_(o).
 21. A polymeric materialcomprising a square array of perpendicularly oriented cylindricaldomains of a first block of a block copolymer within a matrix of asecond block of the block copolymer, the cylindrical domains in a singlearray at a pitch distance of about L_(o) and aligned with adjacentcylindrical domains at a pitch distance of about L_(o).
 22. A polymericmaterial comprising a square array of perpendicularly orientedcylindrical domains of a first block of a block copolymer within amatrix of a second block of the block copolymer, the cylindrical domainsin one dimension in a single row at a pitch distance of about L_(o) andaligned with cylindrical domains in a second dimension at a pitchdistance of about L_(o).
 23. A polymeric material comprising: anannealed block copolymer material within adjacently spaced aparttrenches, ends of the trenches being aligned; the block copolymermaterial comprising a rectangular array of cylindrical domains of afirst block of the block copolymer within a matrix of a second block ofthe block copolymer, the cylindrical domains within each trench in asingle array at a pitch distance of about L_(o) and aligned with thecylindrical domains in adjacent trenches at a pitch distance of about2*L_(o), wherein the single array within each trench comprises nperpendicular oriented cylinders between two parallel-orientedcylinders.
 24. A polymeric material comprising a rectangular array ofcylindrical domains of a first block of a block copolymer within amatrix of a second block of the block copolymer, the cylindrical domainsin one dimension comprising n perpendicular oriented cylinders betweentwo parallel-oriented cylinders in a single row at a pitch distance ofabout L_(o), said cylindrical domains aligned with cylindrical domainsin a second dimension at a pitch distance of about 2*L_(o).